Temperature stability of the piezoelectric and elastic response of dc biased [001] and [110] oriented Pb(Zn1∕3Nb2∕3)O3-PbTiO3 single crystals

Temperature and field dependent investigations of the longitudinal electromechanical properties of [001]- and [110]-oriented 0.955Pb(Zn1∕3Nb2∕3)O3-0.045PbTiO3 single crystals have been performed. Electromechanical equivalence was found between [001] and [110] orientations in the ferroelectric rhombohedral FEr phase region, but not in the ferroelectric tetragonal FEt one. A dc bias of 0.4 MV∕m did not affect this equivalence. Softening of the dielectric constant (K), piezoelectric coefficient (d33), and Young’s modulus (Y) were observed along both the [001] and [110] orientations in the FEr phase region on heating towards the FEt one. Above the FEr-FEt phase transition, a significant anisotropy was observed in the electromechanical and elastic coefficients. These results demonstrate that the enhanced length extensional (33-mode) electromechanical coupling k33 of rhombohedral crystals far from the morphotropic phase boundary is not constrained to the ⟨001⟩ orientation, but rather to the (110) plane.